For those looking for a solution, you have to add an id to the Rich Text Editor, add an html element and paste this code replacing YOUREDITORID by the id you used:
<script>
const editorEle = document.getElementById('YOUREDITORID ');
// Handle the `paste` event
editorEle.addEventListener('paste', function (e) {
// Prevent the default action
e.preventDefault();
// Get the copied text from the clipboard
const text = e.clipboardData
? (e.originalEvent || e).clipboardData.getData('text/plain')
: // For IE
window.clipboardData
? window.clipboardData.getData('Text')
: '';
if (document.queryCommandSupported('insertText')) {
document.execCommand('insertText', false, text);
} else {
// Insert text at the current position of caret
const range = document.getSelection().getRangeAt(0);
range.deleteContents();
const textNode = document.createTextNode(text);
range.insertNode(textNode);
range.selectNodeContents(textNode);
range.collapse(false);
const selection = window.getSelection();
selection.removeAllRanges();
selection.addRange(range);
}
});
</script>